1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Internet Control Message Protocol (ICMPv6) 4 * Linux INET6 implementation 5 * 6 * Authors: 7 * Pedro Roque <roque@di.fc.ul.pt> 8 * 9 * Based on net/ipv4/icmp.c 10 * 11 * RFC 1885 12 */ 13 14 /* 15 * Changes: 16 * 17 * Andi Kleen : exception handling 18 * Andi Kleen add rate limits. never reply to a icmp. 19 * add more length checks and other fixes. 20 * yoshfuji : ensure to sent parameter problem for 21 * fragments. 22 * YOSHIFUJI Hideaki @USAGI: added sysctl for icmp rate limit. 23 * Randy Dunlap and 24 * YOSHIFUJI Hideaki @USAGI: Per-interface statistics support 25 * Kazunori MIYAZAWA @USAGI: change output process to use ip6_append_data 26 */ 27 28 #define pr_fmt(fmt) "IPv6: " fmt 29 30 #include <linux/module.h> 31 #include <linux/errno.h> 32 #include <linux/types.h> 33 #include <linux/socket.h> 34 #include <linux/in.h> 35 #include <linux/kernel.h> 36 #include <linux/sockios.h> 37 #include <linux/net.h> 38 #include <linux/skbuff.h> 39 #include <linux/init.h> 40 #include <linux/netfilter.h> 41 #include <linux/slab.h> 42 43 #ifdef CONFIG_SYSCTL 44 #include <linux/sysctl.h> 45 #endif 46 47 #include <linux/inet.h> 48 #include <linux/netdevice.h> 49 #include <linux/icmpv6.h> 50 51 #include <net/ip.h> 52 #include <net/sock.h> 53 54 #include <net/ipv6.h> 55 #include <net/ip6_checksum.h> 56 #include <net/ping.h> 57 #include <net/protocol.h> 58 #include <net/raw.h> 59 #include <net/rawv6.h> 60 #include <net/seg6.h> 61 #include <net/transp_v6.h> 62 #include <net/ip6_route.h> 63 #include <net/addrconf.h> 64 #include <net/icmp.h> 65 #include <net/xfrm.h> 66 #include <net/inet_common.h> 67 #include <net/dsfield.h> 68 #include <net/l3mdev.h> 69 70 #include <linux/uaccess.h> 71 72 static DEFINE_PER_CPU(struct sock *, ipv6_icmp_sk); 73 74 static int icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 75 u8 type, u8 code, int offset, __be32 info) 76 { 77 /* icmpv6_notify checks 8 bytes can be pulled, icmp6hdr is 8 bytes */ 78 struct icmp6hdr *icmp6 = (struct icmp6hdr *) (skb->data + offset); 79 struct net *net = dev_net_rcu(skb->dev); 80 81 if (type == ICMPV6_PKT_TOOBIG) 82 ip6_update_pmtu(skb, net, info, skb->dev->ifindex, 0, sock_net_uid(net, NULL)); 83 else if (type == NDISC_REDIRECT) 84 ip6_redirect(skb, net, skb->dev->ifindex, 0, 85 sock_net_uid(net, NULL)); 86 87 if (!(type & ICMPV6_INFOMSG_MASK)) 88 if (icmp6->icmp6_type == ICMPV6_ECHO_REQUEST) 89 ping_err(skb, offset, ntohl(info)); 90 91 return 0; 92 } 93 94 static int icmpv6_rcv(struct sk_buff *skb); 95 96 static const struct inet6_protocol icmpv6_protocol = { 97 .handler = icmpv6_rcv, 98 .err_handler = icmpv6_err, 99 .flags = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL, 100 }; 101 102 /* Called with BH disabled */ 103 static struct sock *icmpv6_xmit_lock(struct net *net) 104 { 105 struct sock *sk; 106 107 sk = this_cpu_read(ipv6_icmp_sk); 108 if (unlikely(!spin_trylock(&sk->sk_lock.slock))) { 109 /* This can happen if the output path (f.e. SIT or 110 * ip6ip6 tunnel) signals dst_link_failure() for an 111 * outgoing ICMP6 packet. 112 */ 113 return NULL; 114 } 115 sock_net_set(sk, net); 116 return sk; 117 } 118 119 static void icmpv6_xmit_unlock(struct sock *sk) 120 { 121 sock_net_set(sk, &init_net); 122 spin_unlock(&sk->sk_lock.slock); 123 } 124 125 /* 126 * Figure out, may we reply to this packet with icmp error. 127 * 128 * We do not reply, if: 129 * - it was icmp error message. 130 * - it is truncated, so that it is known, that protocol is ICMPV6 131 * (i.e. in the middle of some exthdr) 132 * 133 * --ANK (980726) 134 */ 135 136 static bool is_ineligible(const struct sk_buff *skb) 137 { 138 int ptr = (u8 *)(ipv6_hdr(skb) + 1) - skb->data; 139 int len = skb->len - ptr; 140 __u8 nexthdr = ipv6_hdr(skb)->nexthdr; 141 __be16 frag_off; 142 143 if (len < 0) 144 return true; 145 146 ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr, &frag_off); 147 if (ptr < 0) 148 return false; 149 if (nexthdr == IPPROTO_ICMPV6) { 150 u8 _type, *tp; 151 tp = skb_header_pointer(skb, 152 ptr+offsetof(struct icmp6hdr, icmp6_type), 153 sizeof(_type), &_type); 154 155 /* Based on RFC 8200, Section 4.5 Fragment Header, return 156 * false if this is a fragment packet with no icmp header info. 157 */ 158 if (!tp && frag_off != 0) 159 return false; 160 else if (!tp || !(*tp & ICMPV6_INFOMSG_MASK)) 161 return true; 162 } 163 return false; 164 } 165 166 static bool icmpv6_mask_allow(struct net *net, int type) 167 { 168 if (type > ICMPV6_MSG_MAX) 169 return true; 170 171 /* Limit if icmp type is set in ratemask. */ 172 if (!test_bit(type, net->ipv6.sysctl.icmpv6_ratemask)) 173 return true; 174 175 return false; 176 } 177 178 static bool icmpv6_global_allow(struct net *net, int type, 179 bool *apply_ratelimit) 180 { 181 if (icmpv6_mask_allow(net, type)) 182 return true; 183 184 if (icmp_global_allow(net)) { 185 *apply_ratelimit = true; 186 return true; 187 } 188 __ICMP_INC_STATS(net, ICMP_MIB_RATELIMITGLOBAL); 189 return false; 190 } 191 192 /* 193 * Check the ICMP output rate limit 194 */ 195 static bool icmpv6_xrlim_allow(struct sock *sk, u8 type, 196 struct flowi6 *fl6, bool apply_ratelimit) 197 { 198 struct net *net = sock_net(sk); 199 struct dst_entry *dst; 200 bool res = false; 201 202 if (!apply_ratelimit) 203 return true; 204 205 /* 206 * Look up the output route. 207 * XXX: perhaps the expire for routing entries cloned by 208 * this lookup should be more aggressive (not longer than timeout). 209 */ 210 dst = ip6_route_output(net, sk, fl6); 211 if (dst->error) { 212 IP6_INC_STATS(net, ip6_dst_idev(dst), 213 IPSTATS_MIB_OUTNOROUTES); 214 } else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) { 215 res = true; 216 } else { 217 struct rt6_info *rt = dst_rt6_info(dst); 218 int tmo = net->ipv6.sysctl.icmpv6_time; 219 struct inet_peer *peer; 220 221 /* Give more bandwidth to wider prefixes. */ 222 if (rt->rt6i_dst.plen < 128) 223 tmo >>= ((128 - rt->rt6i_dst.plen)>>5); 224 225 rcu_read_lock(); 226 peer = inet_getpeer_v6(net->ipv6.peers, &fl6->daddr); 227 res = inet_peer_xrlim_allow(peer, tmo); 228 rcu_read_unlock(); 229 } 230 if (!res) 231 __ICMP6_INC_STATS(net, ip6_dst_idev(dst), 232 ICMP6_MIB_RATELIMITHOST); 233 else 234 icmp_global_consume(net); 235 dst_release(dst); 236 return res; 237 } 238 239 static bool icmpv6_rt_has_prefsrc(struct sock *sk, u8 type, 240 struct flowi6 *fl6) 241 { 242 struct net *net = sock_net(sk); 243 struct dst_entry *dst; 244 bool res = false; 245 246 dst = ip6_route_output(net, sk, fl6); 247 if (!dst->error) { 248 struct rt6_info *rt = dst_rt6_info(dst); 249 struct in6_addr prefsrc; 250 251 rt6_get_prefsrc(rt, &prefsrc); 252 res = !ipv6_addr_any(&prefsrc); 253 } 254 dst_release(dst); 255 return res; 256 } 257 258 /* 259 * an inline helper for the "simple" if statement below 260 * checks if parameter problem report is caused by an 261 * unrecognized IPv6 option that has the Option Type 262 * highest-order two bits set to 10 263 */ 264 265 static bool opt_unrec(struct sk_buff *skb, __u32 offset) 266 { 267 u8 _optval, *op; 268 269 offset += skb_network_offset(skb); 270 op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval); 271 if (!op) 272 return true; 273 return (*op & 0xC0) == 0x80; 274 } 275 276 void icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6, 277 struct icmp6hdr *thdr, int len) 278 { 279 struct sk_buff *skb; 280 struct icmp6hdr *icmp6h; 281 282 skb = skb_peek(&sk->sk_write_queue); 283 if (!skb) 284 return; 285 286 icmp6h = icmp6_hdr(skb); 287 memcpy(icmp6h, thdr, sizeof(struct icmp6hdr)); 288 icmp6h->icmp6_cksum = 0; 289 290 if (skb_queue_len(&sk->sk_write_queue) == 1) { 291 skb->csum = csum_partial(icmp6h, 292 sizeof(struct icmp6hdr), skb->csum); 293 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr, 294 &fl6->daddr, 295 len, fl6->flowi6_proto, 296 skb->csum); 297 } else { 298 __wsum tmp_csum = 0; 299 300 skb_queue_walk(&sk->sk_write_queue, skb) { 301 tmp_csum = csum_add(tmp_csum, skb->csum); 302 } 303 304 tmp_csum = csum_partial(icmp6h, 305 sizeof(struct icmp6hdr), tmp_csum); 306 icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr, 307 &fl6->daddr, 308 len, fl6->flowi6_proto, 309 tmp_csum); 310 } 311 ip6_push_pending_frames(sk); 312 } 313 314 struct icmpv6_msg { 315 struct sk_buff *skb; 316 int offset; 317 uint8_t type; 318 }; 319 320 static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) 321 { 322 struct icmpv6_msg *msg = (struct icmpv6_msg *) from; 323 struct sk_buff *org_skb = msg->skb; 324 __wsum csum; 325 326 csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset, 327 to, len); 328 skb->csum = csum_block_add(skb->csum, csum, odd); 329 if (!(msg->type & ICMPV6_INFOMSG_MASK)) 330 nf_ct_attach(skb, org_skb); 331 return 0; 332 } 333 334 #if IS_ENABLED(CONFIG_IPV6_MIP6) 335 static void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) 336 { 337 struct ipv6hdr *iph = ipv6_hdr(skb); 338 struct ipv6_destopt_hao *hao; 339 int off; 340 341 if (opt->dsthao) { 342 off = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO); 343 if (likely(off >= 0)) { 344 hao = (struct ipv6_destopt_hao *) 345 (skb_network_header(skb) + off); 346 swap(iph->saddr, hao->addr); 347 } 348 } 349 } 350 #else 351 static inline void mip6_addr_swap(struct sk_buff *skb, const struct inet6_skb_parm *opt) {} 352 #endif 353 354 static struct dst_entry *icmpv6_route_lookup(struct net *net, 355 struct sk_buff *skb, 356 struct sock *sk, 357 struct flowi6 *fl6) 358 { 359 struct dst_entry *dst, *dst2; 360 struct flowi6 fl2; 361 int err; 362 363 err = ip6_dst_lookup(net, sk, &dst, fl6); 364 if (err) 365 return ERR_PTR(err); 366 367 /* 368 * We won't send icmp if the destination is known 369 * anycast unless we need to treat anycast as unicast. 370 */ 371 if (!READ_ONCE(net->ipv6.sysctl.icmpv6_error_anycast_as_unicast) && 372 ipv6_anycast_destination(dst, &fl6->daddr)) { 373 net_dbg_ratelimited("icmp6_send: acast source\n"); 374 dst_release(dst); 375 return ERR_PTR(-EINVAL); 376 } 377 378 /* No need to clone since we're just using its address. */ 379 dst2 = dst; 380 381 dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), sk, 0); 382 if (!IS_ERR(dst)) { 383 if (dst != dst2) 384 return dst; 385 } else { 386 if (PTR_ERR(dst) == -EPERM) 387 dst = NULL; 388 else 389 return dst; 390 } 391 392 err = xfrm_decode_session_reverse(net, skb, flowi6_to_flowi(&fl2), AF_INET6); 393 if (err) 394 goto relookup_failed; 395 396 err = ip6_dst_lookup(net, sk, &dst2, &fl2); 397 if (err) 398 goto relookup_failed; 399 400 dst2 = xfrm_lookup(net, dst2, flowi6_to_flowi(&fl2), sk, XFRM_LOOKUP_ICMP); 401 if (!IS_ERR(dst2)) { 402 dst_release(dst); 403 dst = dst2; 404 } else { 405 err = PTR_ERR(dst2); 406 if (err == -EPERM) { 407 dst_release(dst); 408 return dst2; 409 } else 410 goto relookup_failed; 411 } 412 413 relookup_failed: 414 if (dst) 415 return dst; 416 return ERR_PTR(err); 417 } 418 419 static struct net_device *icmp6_dev(const struct sk_buff *skb) 420 { 421 struct net_device *dev = skb->dev; 422 423 /* for local traffic to local address, skb dev is the loopback 424 * device. Check if there is a dst attached to the skb and if so 425 * get the real device index. Same is needed for replies to a link 426 * local address on a device enslaved to an L3 master device 427 */ 428 if (unlikely(dev->ifindex == LOOPBACK_IFINDEX || netif_is_l3_master(skb->dev))) { 429 const struct rt6_info *rt6 = skb_rt6_info(skb); 430 431 /* The destination could be an external IP in Ext Hdr (SRv6, RPL, etc.), 432 * and ip6_null_entry could be set to skb if no route is found. 433 */ 434 if (rt6 && rt6->rt6i_idev) 435 dev = rt6->rt6i_idev->dev; 436 } 437 438 return dev; 439 } 440 441 static int icmp6_iif(const struct sk_buff *skb) 442 { 443 return icmp6_dev(skb)->ifindex; 444 } 445 446 /* 447 * Send an ICMP message in response to a packet in error 448 */ 449 void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info, 450 const struct in6_addr *force_saddr, 451 const struct inet6_skb_parm *parm) 452 { 453 struct inet6_dev *idev = NULL; 454 struct ipv6hdr *hdr = ipv6_hdr(skb); 455 struct sock *sk; 456 struct net *net; 457 struct ipv6_pinfo *np; 458 const struct in6_addr *saddr = NULL; 459 bool apply_ratelimit = false; 460 struct dst_entry *dst; 461 struct icmp6hdr tmp_hdr; 462 struct flowi6 fl6; 463 struct icmpv6_msg msg; 464 struct ipcm6_cookie ipc6; 465 int iif = 0; 466 int addr_type = 0; 467 int len; 468 u32 mark; 469 470 if ((u8 *)hdr < skb->head || 471 (skb_network_header(skb) + sizeof(*hdr)) > skb_tail_pointer(skb)) 472 return; 473 474 if (!skb->dev) 475 return; 476 477 rcu_read_lock(); 478 479 net = dev_net_rcu(skb->dev); 480 mark = IP6_REPLY_MARK(net, skb->mark); 481 /* 482 * Make sure we respect the rules 483 * i.e. RFC 1885 2.4(e) 484 * Rule (e.1) is enforced by not using icmp6_send 485 * in any code that processes icmp errors. 486 */ 487 addr_type = ipv6_addr_type(&hdr->daddr); 488 489 if (ipv6_chk_addr(net, &hdr->daddr, skb->dev, 0) || 490 ipv6_chk_acast_addr_src(net, skb->dev, &hdr->daddr)) 491 saddr = &hdr->daddr; 492 493 /* 494 * Dest addr check 495 */ 496 497 if (addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST) { 498 if (type != ICMPV6_PKT_TOOBIG && 499 !(type == ICMPV6_PARAMPROB && 500 code == ICMPV6_UNK_OPTION && 501 (opt_unrec(skb, info)))) 502 goto out; 503 504 saddr = NULL; 505 } 506 507 addr_type = ipv6_addr_type(&hdr->saddr); 508 509 /* 510 * Source addr check 511 */ 512 513 if (__ipv6_addr_needs_scope_id(addr_type)) { 514 iif = icmp6_iif(skb); 515 } else { 516 /* 517 * The source device is used for looking up which routing table 518 * to use for sending an ICMP error. 519 */ 520 iif = l3mdev_master_ifindex(skb->dev); 521 } 522 523 /* 524 * Must not send error if the source does not uniquely 525 * identify a single node (RFC2463 Section 2.4). 526 * We check unspecified / multicast addresses here, 527 * and anycast addresses will be checked later. 528 */ 529 if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) { 530 net_dbg_ratelimited("icmp6_send: addr_any/mcast source [%pI6c > %pI6c]\n", 531 &hdr->saddr, &hdr->daddr); 532 goto out; 533 } 534 535 /* 536 * Never answer to a ICMP packet. 537 */ 538 if (is_ineligible(skb)) { 539 net_dbg_ratelimited("icmp6_send: no reply to icmp error [%pI6c > %pI6c]\n", 540 &hdr->saddr, &hdr->daddr); 541 goto out; 542 } 543 544 /* Needed by both icmpv6_global_allow and icmpv6_xmit_lock */ 545 local_bh_disable(); 546 547 /* Check global sysctl_icmp_msgs_per_sec ratelimit */ 548 if (!(skb->dev->flags & IFF_LOOPBACK) && 549 !icmpv6_global_allow(net, type, &apply_ratelimit)) 550 goto out_bh_enable; 551 552 mip6_addr_swap(skb, parm); 553 554 sk = icmpv6_xmit_lock(net); 555 if (!sk) 556 goto out_bh_enable; 557 558 memset(&fl6, 0, sizeof(fl6)); 559 fl6.flowi6_proto = IPPROTO_ICMPV6; 560 fl6.daddr = hdr->saddr; 561 if (force_saddr) 562 saddr = force_saddr; 563 if (saddr) { 564 fl6.saddr = *saddr; 565 } else if (!icmpv6_rt_has_prefsrc(sk, type, &fl6)) { 566 /* select a more meaningful saddr from input if */ 567 struct net_device *in_netdev; 568 569 in_netdev = dev_get_by_index(net, parm->iif); 570 if (in_netdev) { 571 ipv6_dev_get_saddr(net, in_netdev, &fl6.daddr, 572 inet6_sk(sk)->srcprefs, 573 &fl6.saddr); 574 dev_put(in_netdev); 575 } 576 } 577 fl6.flowi6_mark = mark; 578 fl6.flowi6_oif = iif; 579 fl6.fl6_icmp_type = type; 580 fl6.fl6_icmp_code = code; 581 fl6.flowi6_uid = sock_net_uid(net, NULL); 582 fl6.mp_hash = rt6_multipath_hash(net, &fl6, skb, NULL); 583 security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6)); 584 585 np = inet6_sk(sk); 586 587 if (!icmpv6_xrlim_allow(sk, type, &fl6, apply_ratelimit)) 588 goto out_unlock; 589 590 tmp_hdr.icmp6_type = type; 591 tmp_hdr.icmp6_code = code; 592 tmp_hdr.icmp6_cksum = 0; 593 tmp_hdr.icmp6_pointer = htonl(info); 594 595 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr)) 596 fl6.flowi6_oif = READ_ONCE(np->mcast_oif); 597 else if (!fl6.flowi6_oif) 598 fl6.flowi6_oif = READ_ONCE(np->ucast_oif); 599 600 ipcm6_init_sk(&ipc6, sk); 601 ipc6.sockc.mark = mark; 602 fl6.flowlabel = ip6_make_flowinfo(ipc6.tclass, fl6.flowlabel); 603 604 dst = icmpv6_route_lookup(net, skb, sk, &fl6); 605 if (IS_ERR(dst)) 606 goto out_unlock; 607 608 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst); 609 610 msg.skb = skb; 611 msg.offset = skb_network_offset(skb); 612 msg.type = type; 613 614 len = skb->len - msg.offset; 615 len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) - sizeof(struct icmp6hdr)); 616 if (len < 0) { 617 net_dbg_ratelimited("icmp: len problem [%pI6c > %pI6c]\n", 618 &hdr->saddr, &hdr->daddr); 619 goto out_dst_release; 620 } 621 622 idev = __in6_dev_get(skb->dev); 623 624 if (ip6_append_data(sk, icmpv6_getfrag, &msg, 625 len + sizeof(struct icmp6hdr), 626 sizeof(struct icmp6hdr), 627 &ipc6, &fl6, dst_rt6_info(dst), 628 MSG_DONTWAIT)) { 629 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS); 630 ip6_flush_pending_frames(sk); 631 } else { 632 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr, 633 len + sizeof(struct icmp6hdr)); 634 } 635 636 out_dst_release: 637 dst_release(dst); 638 out_unlock: 639 icmpv6_xmit_unlock(sk); 640 out_bh_enable: 641 local_bh_enable(); 642 out: 643 rcu_read_unlock(); 644 } 645 EXPORT_SYMBOL(icmp6_send); 646 647 /* Slightly more convenient version of icmp6_send with drop reasons. 648 */ 649 void icmpv6_param_prob_reason(struct sk_buff *skb, u8 code, int pos, 650 enum skb_drop_reason reason) 651 { 652 icmp6_send(skb, ICMPV6_PARAMPROB, code, pos, NULL, IP6CB(skb)); 653 kfree_skb_reason(skb, reason); 654 } 655 656 /* Generate icmpv6 with type/code ICMPV6_DEST_UNREACH/ICMPV6_ADDR_UNREACH 657 * if sufficient data bytes are available 658 * @nhs is the size of the tunnel header(s) : 659 * Either an IPv4 header for SIT encap 660 * an IPv4 header + GRE header for GRE encap 661 */ 662 int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type, 663 unsigned int data_len) 664 { 665 struct in6_addr temp_saddr; 666 struct rt6_info *rt; 667 struct sk_buff *skb2; 668 u32 info = 0; 669 670 if (!pskb_may_pull(skb, nhs + sizeof(struct ipv6hdr) + 8)) 671 return 1; 672 673 /* RFC 4884 (partial) support for ICMP extensions */ 674 if (data_len < 128 || (data_len & 7) || skb->len < data_len) 675 data_len = 0; 676 677 skb2 = data_len ? skb_copy(skb, GFP_ATOMIC) : skb_clone(skb, GFP_ATOMIC); 678 679 if (!skb2) 680 return 1; 681 682 skb_dst_drop(skb2); 683 skb_pull(skb2, nhs); 684 skb_reset_network_header(skb2); 685 686 rt = rt6_lookup(dev_net_rcu(skb->dev), &ipv6_hdr(skb2)->saddr, 687 NULL, 0, skb, 0); 688 689 if (rt && rt->dst.dev) 690 skb2->dev = rt->dst.dev; 691 692 ipv6_addr_set_v4mapped(ip_hdr(skb)->saddr, &temp_saddr); 693 694 if (data_len) { 695 /* RFC 4884 (partial) support : 696 * insert 0 padding at the end, before the extensions 697 */ 698 __skb_push(skb2, nhs); 699 skb_reset_network_header(skb2); 700 memmove(skb2->data, skb2->data + nhs, data_len - nhs); 701 memset(skb2->data + data_len - nhs, 0, nhs); 702 /* RFC 4884 4.5 : Length is measured in 64-bit words, 703 * and stored in reserved[0] 704 */ 705 info = (data_len/8) << 24; 706 } 707 if (type == ICMP_TIME_EXCEEDED) 708 icmp6_send(skb2, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 709 info, &temp_saddr, IP6CB(skb2)); 710 else 711 icmp6_send(skb2, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 712 info, &temp_saddr, IP6CB(skb2)); 713 if (rt) 714 ip6_rt_put(rt); 715 716 kfree_skb(skb2); 717 718 return 0; 719 } 720 EXPORT_SYMBOL(ip6_err_gen_icmpv6_unreach); 721 722 static enum skb_drop_reason icmpv6_echo_reply(struct sk_buff *skb) 723 { 724 struct net *net = dev_net_rcu(skb->dev); 725 struct sock *sk; 726 struct inet6_dev *idev; 727 struct ipv6_pinfo *np; 728 const struct in6_addr *saddr = NULL; 729 struct icmp6hdr *icmph = icmp6_hdr(skb); 730 bool apply_ratelimit = false; 731 struct icmp6hdr tmp_hdr; 732 struct flowi6 fl6; 733 struct icmpv6_msg msg; 734 struct dst_entry *dst; 735 struct ipcm6_cookie ipc6; 736 u32 mark = IP6_REPLY_MARK(net, skb->mark); 737 SKB_DR(reason); 738 bool acast; 739 u8 type; 740 741 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) && 742 net->ipv6.sysctl.icmpv6_echo_ignore_multicast) 743 return reason; 744 745 saddr = &ipv6_hdr(skb)->daddr; 746 747 acast = ipv6_anycast_destination(skb_dst(skb), saddr); 748 if (acast && net->ipv6.sysctl.icmpv6_echo_ignore_anycast) 749 return reason; 750 751 if (!ipv6_unicast_destination(skb) && 752 !(net->ipv6.sysctl.anycast_src_echo_reply && acast)) 753 saddr = NULL; 754 755 if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST) 756 type = ICMPV6_EXT_ECHO_REPLY; 757 else 758 type = ICMPV6_ECHO_REPLY; 759 760 memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr)); 761 tmp_hdr.icmp6_type = type; 762 763 memset(&fl6, 0, sizeof(fl6)); 764 if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_ICMPV6_ECHO_REPLIES) 765 fl6.flowlabel = ip6_flowlabel(ipv6_hdr(skb)); 766 767 fl6.flowi6_proto = IPPROTO_ICMPV6; 768 fl6.daddr = ipv6_hdr(skb)->saddr; 769 if (saddr) 770 fl6.saddr = *saddr; 771 fl6.flowi6_oif = icmp6_iif(skb); 772 fl6.fl6_icmp_type = type; 773 fl6.flowi6_mark = mark; 774 fl6.flowi6_uid = sock_net_uid(net, NULL); 775 security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6)); 776 777 local_bh_disable(); 778 sk = icmpv6_xmit_lock(net); 779 if (!sk) 780 goto out_bh_enable; 781 np = inet6_sk(sk); 782 783 if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr)) 784 fl6.flowi6_oif = READ_ONCE(np->mcast_oif); 785 else if (!fl6.flowi6_oif) 786 fl6.flowi6_oif = READ_ONCE(np->ucast_oif); 787 788 if (ip6_dst_lookup(net, sk, &dst, &fl6)) 789 goto out; 790 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0); 791 if (IS_ERR(dst)) 792 goto out; 793 794 /* Check the ratelimit */ 795 if ((!(skb->dev->flags & IFF_LOOPBACK) && 796 !icmpv6_global_allow(net, ICMPV6_ECHO_REPLY, &apply_ratelimit)) || 797 !icmpv6_xrlim_allow(sk, ICMPV6_ECHO_REPLY, &fl6, apply_ratelimit)) 798 goto out_dst_release; 799 800 idev = __in6_dev_get(skb->dev); 801 802 msg.skb = skb; 803 msg.offset = 0; 804 msg.type = type; 805 806 ipcm6_init_sk(&ipc6, sk); 807 ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst); 808 ipc6.tclass = ipv6_get_dsfield(ipv6_hdr(skb)); 809 ipc6.sockc.mark = mark; 810 811 if (icmph->icmp6_type == ICMPV6_EXT_ECHO_REQUEST) 812 if (!icmp_build_probe(skb, (struct icmphdr *)&tmp_hdr)) 813 goto out_dst_release; 814 815 if (ip6_append_data(sk, icmpv6_getfrag, &msg, 816 skb->len + sizeof(struct icmp6hdr), 817 sizeof(struct icmp6hdr), &ipc6, &fl6, 818 dst_rt6_info(dst), MSG_DONTWAIT)) { 819 __ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTERRORS); 820 ip6_flush_pending_frames(sk); 821 } else { 822 icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr, 823 skb->len + sizeof(struct icmp6hdr)); 824 reason = SKB_CONSUMED; 825 } 826 out_dst_release: 827 dst_release(dst); 828 out: 829 icmpv6_xmit_unlock(sk); 830 out_bh_enable: 831 local_bh_enable(); 832 return reason; 833 } 834 835 enum skb_drop_reason icmpv6_notify(struct sk_buff *skb, u8 type, 836 u8 code, __be32 info) 837 { 838 struct inet6_skb_parm *opt = IP6CB(skb); 839 struct net *net = dev_net_rcu(skb->dev); 840 const struct inet6_protocol *ipprot; 841 enum skb_drop_reason reason; 842 int inner_offset; 843 __be16 frag_off; 844 u8 nexthdr; 845 846 reason = pskb_may_pull_reason(skb, sizeof(struct ipv6hdr)); 847 if (reason != SKB_NOT_DROPPED_YET) 848 goto out; 849 850 seg6_icmp_srh(skb, opt); 851 852 nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr; 853 if (ipv6_ext_hdr(nexthdr)) { 854 /* now skip over extension headers */ 855 inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), 856 &nexthdr, &frag_off); 857 if (inner_offset < 0) { 858 SKB_DR_SET(reason, IPV6_BAD_EXTHDR); 859 goto out; 860 } 861 } else { 862 inner_offset = sizeof(struct ipv6hdr); 863 } 864 865 /* Checkin header including 8 bytes of inner protocol header. */ 866 reason = pskb_may_pull_reason(skb, inner_offset + 8); 867 if (reason != SKB_NOT_DROPPED_YET) 868 goto out; 869 870 /* BUGGG_FUTURE: we should try to parse exthdrs in this packet. 871 Without this we will not able f.e. to make source routed 872 pmtu discovery. 873 Corresponding argument (opt) to notifiers is already added. 874 --ANK (980726) 875 */ 876 877 ipprot = rcu_dereference(inet6_protos[nexthdr]); 878 if (ipprot && ipprot->err_handler) 879 ipprot->err_handler(skb, opt, type, code, inner_offset, info); 880 881 raw6_icmp_error(skb, nexthdr, type, code, inner_offset, info); 882 return SKB_CONSUMED; 883 884 out: 885 __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS); 886 return reason; 887 } 888 889 /* 890 * Handle icmp messages 891 */ 892 893 static int icmpv6_rcv(struct sk_buff *skb) 894 { 895 enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED; 896 struct net *net = dev_net_rcu(skb->dev); 897 struct net_device *dev = icmp6_dev(skb); 898 struct inet6_dev *idev = __in6_dev_get(dev); 899 const struct in6_addr *saddr, *daddr; 900 struct icmp6hdr *hdr; 901 u8 type; 902 903 if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) { 904 struct sec_path *sp = skb_sec_path(skb); 905 int nh; 906 907 if (!(sp && sp->xvec[sp->len - 1]->props.flags & 908 XFRM_STATE_ICMP)) { 909 reason = SKB_DROP_REASON_XFRM_POLICY; 910 goto drop_no_count; 911 } 912 913 if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(struct ipv6hdr))) 914 goto drop_no_count; 915 916 nh = skb_network_offset(skb); 917 skb_set_network_header(skb, sizeof(*hdr)); 918 919 if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN, 920 skb)) { 921 reason = SKB_DROP_REASON_XFRM_POLICY; 922 goto drop_no_count; 923 } 924 925 skb_set_network_header(skb, nh); 926 } 927 928 __ICMP6_INC_STATS(dev_net_rcu(dev), idev, ICMP6_MIB_INMSGS); 929 930 saddr = &ipv6_hdr(skb)->saddr; 931 daddr = &ipv6_hdr(skb)->daddr; 932 933 if (skb_checksum_validate(skb, IPPROTO_ICMPV6, ip6_compute_pseudo)) { 934 net_dbg_ratelimited("ICMPv6 checksum failed [%pI6c > %pI6c]\n", 935 saddr, daddr); 936 goto csum_error; 937 } 938 939 if (!pskb_pull(skb, sizeof(*hdr))) 940 goto discard_it; 941 942 hdr = icmp6_hdr(skb); 943 944 type = hdr->icmp6_type; 945 946 ICMP6MSGIN_INC_STATS(dev_net_rcu(dev), idev, type); 947 948 switch (type) { 949 case ICMPV6_ECHO_REQUEST: 950 if (!net->ipv6.sysctl.icmpv6_echo_ignore_all) 951 reason = icmpv6_echo_reply(skb); 952 break; 953 case ICMPV6_EXT_ECHO_REQUEST: 954 if (!net->ipv6.sysctl.icmpv6_echo_ignore_all && 955 READ_ONCE(net->ipv4.sysctl_icmp_echo_enable_probe)) 956 reason = icmpv6_echo_reply(skb); 957 break; 958 959 case ICMPV6_ECHO_REPLY: 960 reason = ping_rcv(skb); 961 break; 962 963 case ICMPV6_EXT_ECHO_REPLY: 964 reason = ping_rcv(skb); 965 break; 966 967 case ICMPV6_PKT_TOOBIG: 968 /* BUGGG_FUTURE: if packet contains rthdr, we cannot update 969 standard destination cache. Seems, only "advanced" 970 destination cache will allow to solve this problem 971 --ANK (980726) 972 */ 973 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) 974 goto discard_it; 975 hdr = icmp6_hdr(skb); 976 977 /* to notify */ 978 fallthrough; 979 case ICMPV6_DEST_UNREACH: 980 case ICMPV6_TIME_EXCEED: 981 case ICMPV6_PARAMPROB: 982 reason = icmpv6_notify(skb, type, hdr->icmp6_code, 983 hdr->icmp6_mtu); 984 break; 985 986 case NDISC_ROUTER_SOLICITATION: 987 case NDISC_ROUTER_ADVERTISEMENT: 988 case NDISC_NEIGHBOUR_SOLICITATION: 989 case NDISC_NEIGHBOUR_ADVERTISEMENT: 990 case NDISC_REDIRECT: 991 reason = ndisc_rcv(skb); 992 break; 993 994 case ICMPV6_MGM_QUERY: 995 igmp6_event_query(skb); 996 return 0; 997 998 case ICMPV6_MGM_REPORT: 999 igmp6_event_report(skb); 1000 return 0; 1001 1002 case ICMPV6_MGM_REDUCTION: 1003 case ICMPV6_NI_QUERY: 1004 case ICMPV6_NI_REPLY: 1005 case ICMPV6_MLD2_REPORT: 1006 case ICMPV6_DHAAD_REQUEST: 1007 case ICMPV6_DHAAD_REPLY: 1008 case ICMPV6_MOBILE_PREFIX_SOL: 1009 case ICMPV6_MOBILE_PREFIX_ADV: 1010 break; 1011 1012 default: 1013 /* informational */ 1014 if (type & ICMPV6_INFOMSG_MASK) 1015 break; 1016 1017 net_dbg_ratelimited("icmpv6: msg of unknown type [%pI6c > %pI6c]\n", 1018 saddr, daddr); 1019 1020 /* 1021 * error of unknown type. 1022 * must pass to upper level 1023 */ 1024 1025 reason = icmpv6_notify(skb, type, hdr->icmp6_code, 1026 hdr->icmp6_mtu); 1027 } 1028 1029 /* until the v6 path can be better sorted assume failure and 1030 * preserve the status quo behaviour for the rest of the paths to here 1031 */ 1032 if (reason) 1033 kfree_skb_reason(skb, reason); 1034 else 1035 consume_skb(skb); 1036 1037 return 0; 1038 1039 csum_error: 1040 reason = SKB_DROP_REASON_ICMP_CSUM; 1041 __ICMP6_INC_STATS(dev_net_rcu(dev), idev, ICMP6_MIB_CSUMERRORS); 1042 discard_it: 1043 __ICMP6_INC_STATS(dev_net_rcu(dev), idev, ICMP6_MIB_INERRORS); 1044 drop_no_count: 1045 kfree_skb_reason(skb, reason); 1046 return 0; 1047 } 1048 1049 void icmpv6_flow_init(const struct sock *sk, struct flowi6 *fl6, u8 type, 1050 const struct in6_addr *saddr, 1051 const struct in6_addr *daddr, int oif) 1052 { 1053 memset(fl6, 0, sizeof(*fl6)); 1054 fl6->saddr = *saddr; 1055 fl6->daddr = *daddr; 1056 fl6->flowi6_proto = IPPROTO_ICMPV6; 1057 fl6->fl6_icmp_type = type; 1058 fl6->fl6_icmp_code = 0; 1059 fl6->flowi6_oif = oif; 1060 security_sk_classify_flow(sk, flowi6_to_flowi_common(fl6)); 1061 } 1062 1063 int __init icmpv6_init(void) 1064 { 1065 struct sock *sk; 1066 int err, i; 1067 1068 for_each_possible_cpu(i) { 1069 err = inet_ctl_sock_create(&sk, PF_INET6, 1070 SOCK_RAW, IPPROTO_ICMPV6, &init_net); 1071 if (err < 0) { 1072 pr_err("Failed to initialize the ICMP6 control socket (err %d)\n", 1073 err); 1074 return err; 1075 } 1076 1077 per_cpu(ipv6_icmp_sk, i) = sk; 1078 1079 /* Enough space for 2 64K ICMP packets, including 1080 * sk_buff struct overhead. 1081 */ 1082 sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024); 1083 } 1084 1085 err = -EAGAIN; 1086 if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0) 1087 goto fail; 1088 1089 err = inet6_register_icmp_sender(icmp6_send); 1090 if (err) 1091 goto sender_reg_err; 1092 return 0; 1093 1094 sender_reg_err: 1095 inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6); 1096 fail: 1097 pr_err("Failed to register ICMP6 protocol\n"); 1098 return err; 1099 } 1100 1101 void icmpv6_cleanup(void) 1102 { 1103 inet6_unregister_icmp_sender(icmp6_send); 1104 inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6); 1105 } 1106 1107 1108 static const struct icmp6_err { 1109 int err; 1110 int fatal; 1111 } tab_unreach[] = { 1112 { /* NOROUTE */ 1113 .err = ENETUNREACH, 1114 .fatal = 0, 1115 }, 1116 { /* ADM_PROHIBITED */ 1117 .err = EACCES, 1118 .fatal = 1, 1119 }, 1120 { /* Was NOT_NEIGHBOUR, now reserved */ 1121 .err = EHOSTUNREACH, 1122 .fatal = 0, 1123 }, 1124 { /* ADDR_UNREACH */ 1125 .err = EHOSTUNREACH, 1126 .fatal = 0, 1127 }, 1128 { /* PORT_UNREACH */ 1129 .err = ECONNREFUSED, 1130 .fatal = 1, 1131 }, 1132 { /* POLICY_FAIL */ 1133 .err = EACCES, 1134 .fatal = 1, 1135 }, 1136 { /* REJECT_ROUTE */ 1137 .err = EACCES, 1138 .fatal = 1, 1139 }, 1140 }; 1141 1142 int icmpv6_err_convert(u8 type, u8 code, int *err) 1143 { 1144 int fatal = 0; 1145 1146 *err = EPROTO; 1147 1148 switch (type) { 1149 case ICMPV6_DEST_UNREACH: 1150 fatal = 1; 1151 if (code < ARRAY_SIZE(tab_unreach)) { 1152 *err = tab_unreach[code].err; 1153 fatal = tab_unreach[code].fatal; 1154 } 1155 break; 1156 1157 case ICMPV6_PKT_TOOBIG: 1158 *err = EMSGSIZE; 1159 break; 1160 1161 case ICMPV6_PARAMPROB: 1162 *err = EPROTO; 1163 fatal = 1; 1164 break; 1165 1166 case ICMPV6_TIME_EXCEED: 1167 *err = EHOSTUNREACH; 1168 break; 1169 } 1170 1171 return fatal; 1172 } 1173 EXPORT_SYMBOL(icmpv6_err_convert); 1174 1175 #ifdef CONFIG_SYSCTL 1176 static struct ctl_table ipv6_icmp_table_template[] = { 1177 { 1178 .procname = "ratelimit", 1179 .data = &init_net.ipv6.sysctl.icmpv6_time, 1180 .maxlen = sizeof(int), 1181 .mode = 0644, 1182 .proc_handler = proc_dointvec_ms_jiffies, 1183 }, 1184 { 1185 .procname = "echo_ignore_all", 1186 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_all, 1187 .maxlen = sizeof(u8), 1188 .mode = 0644, 1189 .proc_handler = proc_dou8vec_minmax, 1190 }, 1191 { 1192 .procname = "echo_ignore_multicast", 1193 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_multicast, 1194 .maxlen = sizeof(u8), 1195 .mode = 0644, 1196 .proc_handler = proc_dou8vec_minmax, 1197 }, 1198 { 1199 .procname = "echo_ignore_anycast", 1200 .data = &init_net.ipv6.sysctl.icmpv6_echo_ignore_anycast, 1201 .maxlen = sizeof(u8), 1202 .mode = 0644, 1203 .proc_handler = proc_dou8vec_minmax, 1204 }, 1205 { 1206 .procname = "ratemask", 1207 .data = &init_net.ipv6.sysctl.icmpv6_ratemask_ptr, 1208 .maxlen = ICMPV6_MSG_MAX + 1, 1209 .mode = 0644, 1210 .proc_handler = proc_do_large_bitmap, 1211 }, 1212 { 1213 .procname = "error_anycast_as_unicast", 1214 .data = &init_net.ipv6.sysctl.icmpv6_error_anycast_as_unicast, 1215 .maxlen = sizeof(u8), 1216 .mode = 0644, 1217 .proc_handler = proc_dou8vec_minmax, 1218 .extra1 = SYSCTL_ZERO, 1219 .extra2 = SYSCTL_ONE, 1220 }, 1221 }; 1222 1223 struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net) 1224 { 1225 struct ctl_table *table; 1226 1227 table = kmemdup(ipv6_icmp_table_template, 1228 sizeof(ipv6_icmp_table_template), 1229 GFP_KERNEL); 1230 1231 if (table) { 1232 table[0].data = &net->ipv6.sysctl.icmpv6_time; 1233 table[1].data = &net->ipv6.sysctl.icmpv6_echo_ignore_all; 1234 table[2].data = &net->ipv6.sysctl.icmpv6_echo_ignore_multicast; 1235 table[3].data = &net->ipv6.sysctl.icmpv6_echo_ignore_anycast; 1236 table[4].data = &net->ipv6.sysctl.icmpv6_ratemask_ptr; 1237 table[5].data = &net->ipv6.sysctl.icmpv6_error_anycast_as_unicast; 1238 } 1239 return table; 1240 } 1241 1242 size_t ipv6_icmp_sysctl_table_size(void) 1243 { 1244 return ARRAY_SIZE(ipv6_icmp_table_template); 1245 } 1246 #endif 1247